Etel Billig, the co-founder of the Illinois Theatre Center in Park Forest, an indefatigable pioneer of professional theater in the Chicago suburbs and a Chicago actress with decades of work on the city's leading stages, died March 28, after suffering a brain aneurysm at her desk at her beloved theater on the previous day.

"Rehearsals were going on at the time," Billig's son, Jonathan, said. "My mother was found by one of the actors." She died later that night.

Billig, who was 79, was still very much in artistic and managerial charge of her 36-year-old, Equity-affiliated theater in Park Forest, which she founded with her late husband, Steve Billig, and which she treated as a parent would a child.

Indeed, she gave a number of now-prominent actors their first big breaks in her old basement space at the Park Forest library, including the Steppenwolf Theatre ensemble member Sally Murphy, Jennifer Lien and Colin Egglesfield. The Oscar-nominated actor Michael Shannon did his first professional work with Billig as his director in "Winterset" by Maxwell Anderson.

"He told us he was 19," Jonathan Billig said. "I think he was worried we would not trust him with the role if he admitted to being only 16."

Many of Billig's loyal subscribers were retired schoolteachers, theaterlovers who had supported Billig for years, if not decades, after the Billigs decided to target teachers early on in their marketing efforts, even as their chosen home, suburban Park Forest, was exploding with growth.

The Illinois Theatre Center was always a small operation but Ms. Billig was proud of its affiliation with the actor's union and fought with fervor for the media coverage she felt her actors and her theater deserved. "She was,' said David Zak, a longtime theater colleague, "a tigress."

Yet perhaps more than any other artistic director in Chicago, Billig understood that small theaters must have the closest of relationships with their supporters. At Billig's theater, a subscription could be renewed merely by a conversation in the lobby and, on several memorable occasions, Billig would interrupt her famously intimate pre-show announcements to make sure that everyone in the house had the view they wanted of the stage.

If her patrons were sick, Ms. Billig would tend them back to health. If they were expected at her theater and did not arrive, Ms. Billig would know and make inquiries after their wellbeing.

Her tastes in theater were broad but always classy, with a particular penchant for writers who relished the spoken word. Outside of her own theater, she also appeared at such Chicago theaters as the Goodman Theatre and taught acting to generations of Chicago-area performers.

Jonathan Billig, who followed his mother into the theater, said that although the opening of the next Illinois Theatre Center show, a Jerry Herman revue, will now be delayed for a few days, "the show will go on, as my mother would have wanted."

Billig is also survived by another son, Curt Billig. Funeral arrangements are pending.